One-piece ignition switch for small internal combustion engines

ABSTRACT

Disclosed herein is a switch construction including a switch support having a protuberance and an electrically nonconducting switch member movable on said support and including a main body and a part extending resiliently from said main body and having an electrically conducting contact biased toward said support and movable, in response to movement of the switch member, between a position of contact with the support when the switch member is in a first position and a position of noncontact with the support when the switch member is in a second position. The part also has a foot which is biased toward the support and which is movable, in response to movement of the switch member, between a position out of engagement with the support when the switch member is in the first position and a position of engagement with the support when the switch member is in the second position. In one embodiment, the foot moves relative to the protuberance to provide an impositive detent for both first and second switch positions. In another embodiment, the foot moves relative to the protuberance to cooperate in establishing engagement between the contact and the support and to provide an impositive detent for at least one switch position.

United States Patent Densow Mar. 14, 1972 [54] ONE-PIECE IGNITION SWITCH FOR SMALL INTERNAL COMBUSTION Matthews ..200/157 X 3,300,594 l/1967 Paine et a1; ..200/166 SD X FOREIGN PATENTS OR APPLICATIONS 1,349,225 -12/1963 France ..200/16 R Primary Examiner--Robert K. Schaffer Assistant Examiner-Robert A. Vanderhye Att0meyRobert E. Clemency, John W. Michael, Gerrit D. Foster, Bayard H. Michael, Paul R. Puemer, Joseph A. Gemignani, Andrew 0. Riteris, Spencer B. Michael and Robert K. Gerling [5 7] ABSTRACT Disclosed herein is a switch construction including a switch support having a protuberance and an electrically nonconducting switch member movable on said support and including a main body and a part extending resiliently from said main body and having an electrically conducting contact biased toward said support and movable, in response to movement of the switch member, between a position of contact with the support when the switch member is in a first position and a position of noncontact with the support when the switch member is in a second position. The part also has a foot which is biased toward the support and which is movable, in response to movement of the switch member, between a position out of engagement with the support when the switch member is in the first position and a position of engagement with the sup port when the switch member is in the second position. In one embodiment, the foot moves relative to the protuberance to provide an impositive detent for both first and second switch positions. In another embodiment, the foot moves relative to the protuberance to cooperate in establishing engagement between the contact and the support and to provide an impositive detent for at least one switch position.

14 Claims, 8 Drawing Figures ONE-PIECE IGNITION SWITCH FOR SMALL INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION contact points, springs, fasteners, etc. Desirably, such switches l 0 should have positive off and/or on" positions, reliable engagement between the contact members to insure electrical conduction and sliding contact to provide for self-cleaning. In addition, switches desirably should not be subject to coming apart because of operating vibrations and preferably should be of low cost.

SUMMARY OF THE INVENTION The invention provides a grounding switch for an ignition system, which switch includes a unitary switch member which is fabricated of resilient, nonconducting plastic and which carries a contact engageable with the support for the switch member to ground a conventional ignition system and thereby prevent engine operation when the switch is electrically conducting. Fabrication from resilient, nonconducting plastic provides the desired spring action for impositive detent action with respect to on" and off positions, as well as for sliding contact to afford self-cleaning. The invention also involves the construction of the frame of the chain saw, together with the shape of the switch member, so that the switch can be assembled simply by sliding the switch member into a slot or notch in the frame of the engine part.

In accordance with the invention, there is provided a switch which is movably mounted on an electrically conducting support and which includes a main body and a part extending resiliently from the main body and including an elongated or cantilevered arm having, adjacent its outer end, a foot and a contact which are selectively engageable with the support when the switch is in its of and on" positions. In the disclosed embodiments, when the switch is in the off position, the contact is electrically engaged with the support to ground the magneto. However, the switch construction is not solely limited to arrangements for grounding magnetos.

Also in accordance with the invention, the frame is provided with a protuberance which cooperates with the switch member to provide, in one embodiment, impositive of and on positions and, in the other embodiment, to provide an impositive "on" position while also serving to assist in locating the contact for engagement with the support to effect electrical conduction between the contact and the support.

One of the principal objects of the invention is the provision of a new and improved switch which is of low cost which can be easily and readily manufactured and assembled and which will provide a long and useful life.

Another principal object of the invention is the provision of a switch having a minimum of parts including a switch member having an arm which is resiliently biased to afford resilient sliding action in response to movement of the switch member.

Still another object of the invention is the provision of a unitary switch member which is fabricated of electrically nonconducting plastic and which has mounted thereon a contact member movable relative to a position of engagement with a metallic support for the switch so as to ground a magneto system electrically coupled to the contact.

Other objects and advantages of the invention will become known by reference to the following description and accompanying drawings.

DRAWINGS FIG. 1 is a perspective view of a chain saw embodying various of the features of the invention.

FIG. 2 is an enlarged view, partially in section, of the switch embodied in the chain saw shown in FIG. 1, the switch being shown in its of position.

FIG. 3 is a view similar to FIG. 2 with the switch being shown in the on position.

FIG. 4 is a view taken generally along line 4-4 of FIG. 2.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4.

FIG. 6 is a view similar to FIG. 2 showing a further embodiment of the invention with the switch being shown in the off" position.

FIG. 7 is a view similar to FIG. 6 with the switch shown in the on position.

FIG. 8 is a view, partially broken away and in section, taking along line 88 of FIG. 6.

GENERAL DESCRIPTION Shown in the drawings is a chain saw 11 an internal combustion engine which includes a magneto and which is mounted on a support or frame 23 including at least two frame members 27 and 29. Movably supported on the frame 23 is a switch 31 which is movable between an off" or conducting position (FIG. 2) in which the magneto is grounded and engine operation is prevented and an on" or nonconducting position (See FIG. 3) affording magneto ignited engine operation. Except as described hereinafter, the chain saw 11 is otherwise of conventional construction known in the art and will not be further described.

In accordance with one feature of the invention, the frame member 27 includes an edge 33 having a notch or cutout 37 and the frame members 27 and 29 are assembled relative to each other so that the frame member 29 closes the open side of the notch 37. With this arrangement, the neck of the switch member, still to be described, can be located in the notch 37 prior to assembly of the frame members 27 and 29, thereby preventing subsequent unwanted disassembly of the switch 31 from the frame 23.

Also in accordance with the invention, both the embodiment shown in FIGS. 2 through 5 and the embodiment shown in FIGS. 6 through 8 include the formation of one of the frame members to include, in spaced relation to said notch 37, a raised shoulder or surface 39 which is adapted to be engaged by a contact or member 41 and a well or depression 43 which is located adjacent to the shoulder 39 and between the shoulder 39 and the notch 37, which well 43 can be depressed beneath the surface of the adjacent portions of the frame member, as shown in FIGS. 6 and 7. Also in accordance with the invention, both the embodiment shown in FIGS. 2 through 5 and the embodiment shown in FIGS. 6 through 8 include the formation on one of the frame members of a protuberance 47 which, as shown in the embodiment of FIGS. 2 and 3, is located between the well 43 and the notch 37 and which, as shown in the embodiment of FIGS. 6 and 7, is located on the opposite side of the notch 37 from the shoulder 39.

More particularly, in the embodiment shown in FIGS. 2 through 5, the switch 31 includes a switch member 51 having an external main body portion 53 which has a larger area than the notch and which is suitably shaped to afford ease of operation by a user. Extending from the main body portion 53 is a part including a neck 57 (See FIG. 5) which is received in the notch 37 and which has a length less than the length of the notch 37 to permit movement in the notch between a first, nonconducting position (See FIG. 2) and a second, conducting position (See FIG. 3). The switch member 51 has at least a portion 59 which has a width greater than the width of the notch 37 and which includes a slot 61 which, in part, defines the neck 57 and receives the inner margin 63 of the frame member 27 to prevent withdrawal of the switch member 51 out of the plane of the notch 37, Le, prevents disassembly of the switch 31 from the frame 23.

The neck 57 is also shaped to guide switch member movement and, in particular, to confine switch member movement to rectilinear movement. While other constructions could be employed, the neck 57 has a width approximating the width of the notch 37.

Extending from one end of the neck 37 is an arm or leg 71 which includes an elongated or cantilevered portion 73 and a foot 77 located in adjacently spaced relation from the end of the elongated portion. Mounted suitably at the end of the elongated portion 73 is the contact member 41 which is electrically connected by a lead 79 to the magneto. Any suitable arrangement can be employed for fixing the contact member 41 on the arm 71, preferably after the contact member 41 and lead 79 have been previously assembled.

The switch member 51 is preferably integrally fabricated, as by molding or otherwise, of plastic which is resilient and which is also a non-conductor of electricity. The elongated arm 71 and extending foot are dimensioned such that when the switch member 51 is in the nonconducting position shown in FIG. 3, i.e., in the engine operating position, the arm 71 is biased toward the frame member 27 but is restrained against further movement toward the frame member by reason of the engagement of the foot 77 with the frame member 27. When the switch member 51 is in the nonconducting position shown in FIG. 3, the contact member 41 is spaced from the shoulder 39.

The shoulder 39 and protuberance 47 are spaced from each other at a distance A" which is greater than the parallel distance B" between the contact member and the end of the foot 77. Because the distance A" is greater than the distance greater bias toward the frame member 27 is provided in the arm 71 when the switch member is in the conducting position (FIG. 2) as compared to the nonconducting position (FIG. 3), thereby obtaining reliable conducting engagement between the contact member 41 and the shoulder 39 when the contact member is in the conducting position shown in FIG. 2. Also when the switch member 31 is in the conducting position, the bottom or end of the foot 77 is spaced from the frame member 27.

In operation of the embodiment shown in FIGS. 2 through 5 when the switch member 51 is moved from the on or nonconducting position shown in FIG. 3 to the off or conducting position shown in FIG. 2, the foot 77 rides up the protube- I rance 47 lifting the contact member 41 for overriding movement into engagement with the shoulder. The amount of bias urging the contact member 41 toward the shoulder 39 can be increased by inclining the shoulder upwardly and away from the protuberance 47. When the switch is moved from the off" or conducting position shown in FIG. 2 toward the on" or nonconducting position shown in FIG. 3, the foot 77 engages the upper surface of the protuberance 47 as the contact member recedes from the shoulder 39.

As can be seen, the well or void 43 between the protuberance 47 and the shoulder 39 affords spacing of the foot from the frame member 27 so that the amount of bias in the arm 71 is controlled by the engagement of the contact member 41 with the shoulder 39.

In FIGS. 6 through 8, there is shown a switch 131 in which like parts to those in the embodiment shown in FIGS. 2 through 5 are given like numbers. More specifically, the switch 131 includes a switch member main body portion 53 designed to be operated by the user and a neck 57 which extends from the main body through a notch 37 to afford guided movement of the switch member between a conducting position (FIG. 6) and a nonconducting position (FIG. 7). Extending from the neck 37 is a first arm 71 with an elongated portion 73 having, in inwardly spaced relation from the outer end thereof, a foot 77 and also supporting adjacent to the outer end thereof, a contact member 41. As with the construction shown in FIGS. 2 through 5, when the switch is in the of or conducting position shown in FIG. 6, the contact member is held in engagement with a shoulder 39 on the frame member 27 by the resilient bias of the arm 71 and the foot 77 is out of engagement with the frame member 27. When the switch 131 is in the on" or nonconducting position (shown in FIG. 7), the foot 77 is held in engagement with the frame member 27 by the biasing action ofthe arm 71 and the contact member 41 is spaced from the frame member 27.

Also extending from the neck in opposing relation to the arm 71 is another arm or leg 81 having a foot 83 which is resiliently biased by the arm 81 into engagement with the adjacent inside surface of the frame member 27. Engagement of the undersurface of the main body portion 53 with the frame member 27 and engagement of the foot 83 and one of the foot 77 and contact member 41 on the arm 71 with the inside of the frame member 27 retains the switch member against unwanted disassembly from the frame.

In the embodiment shown in FIGS. 6 through 8, the inside surface of the frame member 27 includes, on one side of the notch 37, the surface 39 adapted to be engaged by the contact member 41 and, at the other side of the notch 37, a protuberance 47 in the path of the movementof the foot 83 when the switch member is moved between its conducting and nonconducting positions. In operation of the switch shown in FIGS. 6 through 8, the protuberance 47 serves as a detent to impositively locate the switch 131 in both the conducting and nonconducting positions. In the embodiment shown in FIGS. 2 through 5, the protuberance 47 serves an impositive device only with respect to holding the switch in the on" or nonconducting position.

In the embodiment shown in FIGS. 6 through 8, the surface 39 is raised above the general level of the inside surface of the frame member 27 at approximately the same height as the contact is above the inside surface when the foot 77 is engaged with the inside surface. Accordingly, the contact member 41 overrides the surface 39 without difficulty when the switch 131 is moved to the off or conducting position. In order to assure positive electrical engagement between the contact member 41 and the surface 39 under the biasing action of the arm 71, the inside surface of the frame member 27 adjacent to the surface 39 is recessed to provide a well 43 so that when the switch is in the off" or conducting position, the foot 77 is located above the well 43 and spaced from the inside surface of the frame member 27.

As with respect to the switch member of the embodiment shown in FIGS. 2 through 5, the switch member of the embodiment shown in F [OS 6 through 8 is preferably formed of a resilient plastic in such manner that the arms 71 and 81 have a natural bias toward the frame member 27 when the switch member is assembled on the frame.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. A switch comprising a switch support, a non-electrically conducting switch member movable on said support between a first position and a second position and including a main body and a part biased toward said support and extending integrally from said main body and having mounted thereon a contact movable, in response to movement of said switch member, relative to a conductor between a position of contact when said switch member is in said first position and a position of non-contact when said switch member is in said second position, said part also having integrally formed thereon a foot movable, in response to movement of said switch member, between a position out of engagement with said support when said switch member is in said first position and a position of engagement with said support when said switch member is in said second position.

2. A switch in accordance with claim 1 wherein said switch support includes a surface constituting the other conductor.

3. A switch in accordance with claim 2 wherein said support includes a protuberance and an opening through which said switch member extends and said surface is located on the remote side of said protuberance with respect to said opening.

4. A switch in accordance with claim 3 wherein said part integrally includes an arm resiliently biased toward said support and integrally including said foot which is located on one side of said protuberance when said switch is in said second position, and which is located on the other side of said protuberance when said switch is in said first position, said arm also having mounted thereon said contact.

5. A switch in accordance with claim 2 wherein said support includes a protuberance and an opening through which said switch member extends and said surface is located on the remote side of said opening with respect to said protuberance.

6. A switch in accordance with claim 5 wherein said support includes a well located between said surface and said opening and wherein said part integrally includes a first arm resiliently biased toward said support and integrally including said first mentioned foot which is located above said well and spaced from said support when said switch member is in said first position, said part also integrally including a second resilient arm biased toward said support and extending in the opposite direction from said first arm and integrally including a second foot located on one side of said protuberance when said switch is in said first position, said second foot being located on the other side of said protuberance when said switch member is in said second position.

7. A switch in accordance with claim 6 wherein said first arm supports said contact,

8. A switch in accordance with claim 1 wherein said support includes a notch and wherein said part includes a neck received in said notch and having one dimension less than said notch to afford said switch member movement.

9. A switch in accordance with claim 8 wherein said part includes a slot receiving one margin of said notch.

10. A switch in accordance with claim 1 wherein said support includes a notch and said switch member includes means preventing disassembly of said switch member from said support.

. 11. A switch in accordance with claim 10 wherein said means for preventing disassembly of said switch member from said support includes a slot formed on said switch member and receiving one margin of said support.

12. A switch in accordance with claim 10 wherein said part integrally includes a resilient arm biased toward said support and integrally including said foot and having mounted thereon said contact.

13. A switch in accordance with claim 1 wherein said support includes a protuberance and wherein said part integrally includes a first resilient arm biased toward said support and having mounted thereon said contact and a second resilient arm extending in the opposite direction from said first arm, being biased toward said support, and integrally including another foot engaged with said support and movable relative to positions on opposite sides of said protuberance.

14. A chain saw comprising an engine having a magneto, a frame supporting said engine and having a first member and a second member with an edge having a notch, said second member being assembled to said first member with said edge in adjacent relation to said first member, said second member being of metallic construction and including a protuberance spaced from said notch and a surface spaced from said protuberance on the remote side from said notch, a metallic contact connected with said magneto and operative when engaged with said surface to prevent operation of said magneto to fire said engine, and a non-metallic unitary switch member having an integrally extending neck received in said notch and including a slot receiving one margin of said notch to afford sliding movement of said switch member relative to said second member between a first position and a second position, said switch member also integrally including an elongated arm which extends resiliently from said neck, which is biased toward said second member, which carries said contact, and which integrally includes a foot located for movement, in response to movement of said switch member, over said protuberance between a position on one side of said protuberance in engagement with said second member and with said contact spaced from said surface when said switch member is in a first position and another position on the other side of said protuberance in spaced relation from said second member and with said contact in engagement with said surface when said switch member is in another position. 

1. A switch comprising a switch support, a non-electrically conducting switch member movable on said support between a first position and a second position and including a main body and a part biased toward said support and extending integrally from said main body and having mounted thereon a contact movable, in response to movement of said switch member, relative to a conductor between a position of contact when said switch member is in said first position and a position of non-contact when said switch member is in said second position, said part also having integrally formed thereon a foot movable, in response to movement of said switch member, between a position out of engagement with said support when said switch member is in said first position and a position of engagement with said support when said switch member is in said second position.
 2. A switch in accordance with claim 1 wherein said switch support includes a surface constituting the other conductor.
 3. A switch in accordance with claim 2 wherein said support includes a protuberance and an opening through which said switch member extends and said surface is located on the remote side of said protuberance with respect to said opening.
 4. A switch in accordance with claim 3 wherein said part integrally includes an arm resiliently biased toward said support and integrally including said foot which is located on one side of said protuberance when said switch is in said second position, and which is located on the other side of said protuberance when said switch is in said first position, said arm also having mounted thereon said contact.
 5. A switch in accordance with claim 2 wherein said support includes a protuberance and an opening through which said switch member extends and said surface is located on the remote side of said opening with respect to said protuberance.
 6. A switch in accordance with claim 5 wherein said support includes a well located between said surface and said opening and wherein said part integrally includes a first arm resiliently biased toward said support and integrally including said first mentioned foot which is located above said well and spaced from said support when said switch member is in said first position, said part also integrally including a second resilient arm biased toward said support and extending in the opposite direction from said first arm and integrally including a second foot located on one side of said protuberance when said switch is in said first position, said second foot being located on the other side of said protuberance when said switch member is in said second position.
 7. A switch in accordance with claim 6 wherein said first arm supports said contact.
 8. A switch in accordance with claim 1 wherein said support includes a notch and wherein said part includes a neck received in said notch and having one dimension less than said notch to afford said switch member movement.
 9. A switch in accordance with claim 8 wherein said part includes a slot receiving one margin of said notch.
 10. A switch in accordance with claim 1 wherein said support includes a notch and said switch member includes means preventing disassembly of said switch member from said support.
 11. A switch in accordance with claim 10 wherein said means for preVenting disassembly of said switch member from said support includes a slot formed on said switch member and receiving one margin of said support.
 12. A switch in accordance with claim 10 wherein said part integrally includes a resilient arm biased toward said support and integrally including said foot and having mounted thereon said contact.
 13. A switch in accordance with claim 1 wherein said support includes a protuberance and wherein said part integrally includes a first resilient arm biased toward said support and having mounted thereon said contact and a second resilient arm extending in the opposite direction from said first arm, being biased toward said support, and integrally including another foot engaged with said support and movable relative to positions on opposite sides of said protuberance.
 14. A chain saw comprising an engine having a magneto, a frame supporting said engine and having a first member and a second member with an edge having a notch, said second member being assembled to said first member with said edge in adjacent relation to said first member, said second member being of metallic construction and including a protuberance spaced from said notch and a surface spaced from said protuberance on the remote side from said notch, a metallic contact connected with said magneto and operative when engaged with said surface to prevent operation of said magneto to fire said engine, and a non-metallic unitary switch member having an integrally extending neck received in said notch and including a slot receiving one margin of said notch to afford sliding movement of said switch member relative to said second member between a first position and a second position, said switch member also integrally including an elongated arm which extends resiliently from said neck, which is biased toward said second member, which carries said contact, and which integrally includes a foot located for movement, in response to movement of said switch member, over said protuberance between a position on one side of said protuberance in engagement with said second member and with said contact spaced from said surface when said switch member is in a first position and another position on the other side of said protuberance in spaced relation from said second member and with said contact in engagement with said surface when said switch member is in another position. 